Industry Resources – Northlake Steel http://northlakesteel.com Mon, 02 Apr 2018 15:51:19 +0000 en-US hourly 1 Out of Roundness http://northlakesteel.com/blog/out-of-roundness/ Mon, 12 Mar 2018 19:12:09 +0000 http://northlakesteel.com/?p=1161 Out of Roundness on Cold Finished Steel Products Let us first understand that it is not sufficient just to measure the diameter of the shaft in different places with a micrometer, with the difference in readings representing out of roundness.  There will be consequences to this; the most being it can affect the fit between […]

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Out of Roundness on Cold Finished Steel Products

Let us first understand that it is not sufficient just to measure the diameter of the shaft in different places with a micrometer, with the difference in readings representing out of roundness.  There will be consequences to this; the most being it can affect the fit between components (ie: a bearing on a shaft).  To accomplish accurate out of roundness readings, the v-block is the most widely affordable and accepted for shop purposes.  This technique is done by placing the shaft in a v-block, then rotating it while in contact with a dial indicator.  Understand that this three point method is influenced by the number of lobes and the angle of the v-block.

Out of Roundness

V-Block for Measuring Out of Roundness

Methods of Measuring

Since we know the angle of the v-block will influence the out of roundness readings, Northlake keeps multiple v-blocks on hand for checking the different diameters of shafting we produce.  To check out of roundness using v-blocks there are two methods.  The first method is to place the bar stock in two v-blocks which will usually be at an even distance from center.  While rotating the piece it will move the dial indicator.  Be careful on this method as you are only using two supports, and with long length + small diameter bars, you will get a wobble.  The second method, and preferred by Northlake, is to invert the v-block and mount the dial indicator on top (see picture).  As a result, this is more efficient and we can check material in process to make adjustments as needed.

Causes and Solutions

Now that we know how to check roundness, lets look at the causes.  The material in hot roll form will be the first indicator to out of roundness.  Here at Northlake, we work diligently with our suppliers to get the best product available for production.  Next we look at what’s going on in process with our centerless grinders.  If we happen to incur out of roundness, this will generally point to several machine issues that require attention.  Some examples include the angle of the regulating wheel, proper coolant flow & level, grinding wheel composition vs. material being processed.  Another very important factor is the height and top angle of the work rest blade.  This helps with rounding a shaft.  Work rest blades set slightly above center will help out of roundness issues (too much and you might cause chatter).  Consequently, work rest blades set below center could cause out of roundness.

Final Notes

In conclusion, there are many factors that require attention.  Northlake has the experience and knowledge necessary to accomplish a superior product above the rest.  Feel free to contact our sales department with any questions you might have at (P) 888-278-4682.

Northlake Steel Corp

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Ra Surface Finish and Roughness Average http://northlakesteel.com/blog/ra-surface-finish/ Thu, 03 Nov 2016 18:39:07 +0000 http://northlakesteel.com/?p=782 Ra Surface Finish (Roughness Average) When measuring how smooth a turned, ground & polished (TGP), chrome plated hydraulic cylinder rod, or any other cold finished bar, the primary reading or parameter used is Ra surface finish.  There are many other parameters to measure surface finish by, a number well over 100.  But today we will focus on […]

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Ra Surface Finish (Roughness Average)

When measuring how smooth a turned, ground & polished (TGP), chrome plated hydraulic cylinder rod, or any other cold finished bar, the primary reading or parameter used is Ra surface finish.  There are many other parameters to measure surface finish by, a number well over 100.  But today we will focus on this most common in the cold finished steel bar industry, Ra surface finish.

What is Surface Finish?

In a nutshell, surface finish is how smooth or rough the surface of the bar or other medium is.  The smoother the finish, the lower the Ra number will be.  If you look closely at the surface of the steel bar through a microscope, the actual geometry of the surface will be irregular.  It will have peaks and valleys of varying heights and depths.

Looking at the example wavelength below, you can see the many peaks and valleys of the bar surface over the 4mm (0.1575″) test sample length.  The resultant Ra surface finish of this part is 0.164 µm (micrometers), or 6 µin (microinches).  A 6 Ra (µin) is a very smooth polished surface.

Ra surface finish actual profile

Actual surface profile showing the Ra surface finish of 0.164 µm (6 µin microinch) on a ground & polished steel bar.

NSC Shafting Corner

Ground & polished steel bars with a 6-8 Ra µin surface finish

The photo of the ground & polished steel bars show what the surface finish looks like when visually looking at the surface.  It looks nearly like a mirror finish, smooth to the touch if you trace your hand along the bar.  When you look at the surface geometry with a measuring device or microscope, there are actually many peaks & valleys which are too small for the human eye to see.

 

 

What is Ra Surface Finish?

Ra stands for Roughness Average.  In past years Ra was also known as Center Line Average (CLA), or Arithmetic Average (AA), but today Ra is the most commonly used surface finish parameter in the steel industry.

What Ra measures is the average distance (or height) of the peaks & valleys from the mean line.  Most drawings and prints you see will have a Ra surface finish requirement called out on it.  A device called a profilometer can quickly and easily measure the surface finish of a steel bar.

In the example below, we see a drawing of a sample surface profile.  This sample profile has peaks & valleys, along with a number value indicating their distance from the mean line at given points along the bar sample area.  The numbers can be microinches or micrometers.

Ra Surface Finish Example Drawing

Example of how Ra surface finish is calculated.  The heights of the peaks & valleys are averaged.

 Ra Surface Finish in Summary, and Why it’s Important

Surface finish and Ra are important to steel bars, shafts, and chrome plated hydraulic cylinder rods.  It will influence qualities such as the lubrication, ability to hold pressure, friction, resistance to corrosion, noise reduction, and visual appeal to name a few.  Keeping the peaks to a minimum is helpful to reduce wear on a bearing or seal.  Allowing the presence of valleys will help the same part retain oil or lubricant, also increasing the life of the bearing or seal.  Rougher surfaces are more likely to collect and absorb moisture or water between the peaks and valleys, which can hasten corrosion and rust forming on the steel bar surface.  Smoother & finer surfaces will resist this corroding process better.

Northlake Steel Corporation

We employ the latest in polishing and super polishing techniques to supply you with any surface finish needed.  Whether you’re looking for a specific Ra finish, or if you need a super polish with multiple parameters like Rmr, Rk, Rpk, Rvk, Rz, Rmax, or any of the 100+ options.  Northlake will work with you and provide the steel bars to all of your required specifications.  We also have the ability to provide detailed inspection forms showing results of measurements all along the bar, and on multiple planes around the bar.  With the ability to grind & polish to 16″ diameter and 75′ long, we look forward to meeting your challenge!

Contact us online or call 888-278-4682 for more information.

 

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Tolerances Charts http://northlakesteel.com/blog/tolerances-charts/ http://northlakesteel.com/blog/tolerances-charts/#respond Fri, 20 May 2016 09:41:03 +0000 http://northlakesteel.com/?p=97 Turned, Ground and Polished Shafting TG&P Stock Items Nominal Tolerance 1045 4140HT 1/2” .4985/.4995 x 5/8” .6235/.6245 x 3/4” .7485/.7495 x 7/8” .8735/.8745 x 1” .9985/.9995 x x 1-1/8” 1.1235/1.1245 x 1-3/16” 1.1860/1.1870 x x 1-1/4” 1.2485/1.2495 x x 1-3/8” 1.3735/1.3745 x 1-7/16” 1.4360/1.4370 x x 1-1/2” 1.4985/1.4995 x x 1-11/16” 1.6855/1.6870 x 1-3/4” 1.7480/1.7495 […]

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Turned, Ground and Polished Shafting

TG&P Stock Items

Nominal Tolerance 1045 4140HT
1/2” .4985/.4995 x
5/8” .6235/.6245 x
3/4” .7485/.7495 x
7/8” .8735/.8745 x
1” .9985/.9995 x x
1-1/8” 1.1235/1.1245 x
1-3/16” 1.1860/1.1870 x x
1-1/4” 1.2485/1.2495 x x
1-3/8” 1.3735/1.3745 x
1-7/16” 1.4360/1.4370 x x
1-1/2” 1.4985/1.4995 x x
1-11/16” 1.6855/1.6870 x
1-3/4” 1.7480/1.7495 x x
1-7/8” 1.8730/1.8745 x
1-15/16” 1.9355/1.9370 x x
2” 1.9980/1.9995 x x
2-3/16” 2.1855/2.1870 x
2-1/4” 2.2480/2.2495 x
2-7/16” 2.4355/2.4370 x x
2-1/2” 2.4980/2.4995 x x
2-11/16” 2.6855/2.6870 x
2-3/4” 2.7480/2.7495 x
2-15/16” 2.9350/2.9370 x x
3” 2.9975/2.9995 x x
3-7/16” 3.4340/3.4370 x x
3-1/2” 3.4965/3.4995 x x
3-3/4” 3.7465/3.7495 x
3-15/16” 3.9340/3.9370 x x
4” 3.9965/3.9995 x x
4-7/16” 4.4340/4.4370 x x
4-1/2” 4.4965/4.4995 x x
5” 4.9970/5.0000 x
6” 5.9970/6.0000 x
7” 6.9970/7.0000 x
20MM .7859/.7869 x
25MM .9827/.9837 x x
30MM 1.1796/1.1806 x x
40MM 1.5733/1.5743 x
50MM 1.9665/1.9680 x x
60MM 2.3602/2.3617 x
80MM 3.1471/3.1491 x
100MM 3.9340/3.9370 x x

SIZE TOLERANCES FOR TURNED, GROUND AND POLISHED (TG&P)
ROUNDS CARBON, ALLOY & STAINLESS BAR

Diameter ASTM Tolerances Northlake Tolerances
to 1-1/2 + .0000 / – .0010 + .0000 / – .0010
> 1-1/2 to < 2 + .0000 / – .0015 + .0000 / – .0010
2 to < 2-1/2 + .0000 / – .0015 + .0000 / – .0015
2-1/2 to 3 + .0000 / – .0020 + .0000 / – .0015
> 3 to 4 + .0000 / – .0030 + .0000 / – .0020
> 4 to 6 + .0000 / – .0040 + .0000 / – .0030
> 6 to 10 + .0000 / – .0050 + .0000 / – .0030
> 10 to 16 + .0000 / – .0050 + .0000 / – .0040

Linear Shafting Stock Items

1060 STANDARD LINEAR SHAFTING SIZES

Nominal Size Class 1 Class 2 Class 3
1/4” .2495/.2490
3/8” .3745/.3740 .3750/.3748
1/2” .4995/.4990 .5000/.4998
5/8” .6245/.6240
3/4” .7490/.7485 .7490/.7485
7/8” .8745/.8740
1” .9995/.9990 .9990/.9985 1.0000/.9998
1-1/8” 1.1245/1.1240
1-1/4” 1.2495/1.2490 1.2490/1.2485
1-3/8” 1.3745/1.3740
1-1/2” 1.4994/1.4989 1.4989/1.4984
1-3/4” 1.7495/1.7490
2” 1.9994/1.9987 1.9987/1.9980 2.0000/1.9997
2-1/4” 2.2493/2.2485
2-1/2” 2.4993/2.4985 2.4985/2.4977
3” 2.9992/2.9983 2.9983/2.9974 3.0000/2.9996
3-1/2” 3.4990/3.4980
4” 3.9988/3.9976 3.9976/3.9964
1060 Metric Sizes
Nominal Size Class M
8 mm .3150/.3146
10 mm .3937/.3932
12 mm .4724/.4720
16 mm .6299/.6295
20 mm .7874/.7869
25 mm .9843/.9838
30 mm 1.1811/1.1806
40 mm 1.5748/1.5743
50 mm 1.9685/1.9679
60 mm 2.3622/2.3615
80 3.1496/3.1489
440C Stainless
Nominal Size Class 1
1/2” .4995/.4990
5/8” .6245/.6240
3/4” .7490/.7485
1” .9995/.9990
1-1/4” 1.2495/1.2490
1-1/2” 1.4994/1.4989
2” 1.9994/1.9987

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Conversion Charts http://northlakesteel.com/blog/conversion-charts/ http://northlakesteel.com/blog/conversion-charts/#respond Fri, 20 May 2016 09:32:12 +0000 http://northlakesteel.com/?p=94 The following Conversion Charts provide useful steel related information and references for products we regularly stock. Hardness Conversion Charts Click here to view and print a handy hardness conversion chart which includes conversions for Rockwell C (HRc), Rockwell A (HRa), Brinell (Bhn), Vickers (Hv), Scleroscope.  Also includes approximate tensile strength values. Millimeter to Inch Conversion Charts Click here […]

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The following Conversion Charts provide useful steel related information and references for products we regularly stock.

Hardness Conversion Charts

Click here to view and print a handy hardness conversion chart which includes conversions for Rockwell C (HRc), Rockwell A (HRa), Brinell (Bhn), Vickers (Hv), Scleroscope.  Also includes approximate tensile strength values.

Millimeter to Inch Conversion Charts

Click here to view and print our mm to inch conversion chart w/ decimal to fraction equivalents.

Northlake Hardness Conversion Charts

Northlake hardness conversion charts

Northlake mm to inch conversion charts

Northlake mm to inch conversion charts

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Industry Glossary Terms http://northlakesteel.com/blog/industry-glossary-terms/ http://northlakesteel.com/blog/industry-glossary-terms/#respond Fri, 20 May 2016 09:29:58 +0000 http://northlakesteel.com/?p=92 Centerless Bar Grinding Centerless bar grinding is a method used to remove material.  Unlike centered grinding, there is no spindle.  The metal or workpiece is placed between the regulating wheel and the grinding wheel.  It is supported by the work blade.  The wheels are tilted at various angles to achieve the desired effect. Cold Finished […]

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Centerless Bar Grinding

Centerless bar grinding is a method used to remove material.  Unlike centered grinding, there is no spindle.  The metal or workpiece is placed between the regulating wheel and the grinding wheel.  It is supported by the work blade.  The wheels are tilted at various angles to achieve the desired effect.

Cold Finished Steel

The process of re-working steel without using heat.  These processes are typically identified as cold drawn; turned, ground and polished; centerless ground; and turned.  Depending on the process, cold finishing can be used to improve surface finish, straightness, and mechanical properties.

Cold Drawn

The process of pushing and pulling a hot rolled steel bar through a die with an exit diameter of lesser size than the hot roll.   This process produces a clean uniform surface, tighter than hot roll size tolerance, an overall increase in mechanical properties (ex: tensile and yield strength), and enhanced machinability.

Induction Hardening/Heat Treating

Induction hardening/heat treating is a process used for surface hardening.  The bar or tube is run through an electromagnetic induction coil and then immediately quenched.  The electromagnet is used to create alternating current (AC) to pass through the metal.  Eddy currents are generated within the metal, causing resistance and leading to Joule heating of the metal. The frequency of the AC can be changed depending on the size, metal type and depth needed.

Laser Cladding

Laser cladding is a process that bonds together dissimilar materials.  A powder, usually with a metallic nature, or a wire feedstock material is melted and injected into the system. The laser coats the specified parts with the powder.

 

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Industry Information http://northlakesteel.com/blog/industry-information/ http://northlakesteel.com/blog/industry-information/#respond Fri, 20 May 2016 09:28:48 +0000 http://northlakesteel.com/?p=90       Below are a few links that we find useful. These web sites and institutions have a lot of information to keep you up to date on both the domestic and international steel markets. Industry News The American Iron and Steel Institute (AISI) is a political advocate for American manufacturing companies.  AISI publishes […]

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Below are a few links that we find useful. These web sites and institutions have a lot of information to keep you up to date on both the domestic and international steel markets.

Industry News

Steel Standards 

ASTM Member Blue LogoNorthlake Steel is a proud ASTM Participating Member.

  • ASTM International was formerly known as The American Society for Testing and Materials and is the producer of standards for many of the global steel markets.

Educational 

  • ASM International provides educational material on anything from Metallurgy for Non-Metallurgist to Failures Analysis.  ASM provides an online member forum, courses, and textbooks for engineering and science professionals.

Steel Calculations 

  • Steel Mills of the World features many conversion calculations that you may find useful.   They have everything from calculating the theoretical weight of a bar to pressure and stress conversion.

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